Use of newer combined hormonal contraceptives may be associated with reduced ovarian
cancer risk

The risk reduction was greater with increasing duration of use and persisted for several
years after discontinuation, although there was no observed effect with use of progestogen-only
products.

Compared to no use of contemporary combined hormonal contraceptives, current or former
use was associated with reduced risk of ovarian cancer in women of reproductive age,
a recent prospective study found.

The final study population included 1,879,227 women. The researchers categorized participants
as never users (no record of receiving hormonal contraception), current or recent
users (≤1 year after stopping use), or former users (>1 year after stopping
use) of different hormonal contraceptives. Results were published online on Sept.
26 by the BMJ.

Relative risk among current/recent users decreased with increasing duration (from
0.82 [95% CI, 0.59 to 1.12] with ≤1 year of use to 0.26 [95% CI, 0.16 to 0.43]
with >10 years of use; P<0.001 for trend). The risk reduction with former use diminished with time since
discontinuation and was not significant by 10 years after last use. There was little
difference in risk estimates by tumor type or progestogen content of combined oral
contraceptives, but use of progestogen-only products was not associated with ovarian
cancer risk (although few women were exclusive users of such products, limiting statistical
power).

Among ever users, the reduction in the age-standardized absolute rate of ovarian cancer
was 3.2 per 100,000 person-years. Based on a relative risk of 0.66 for the never-use
versus ever-use categories, hormonal contraception prevented 21% of ovarian cancers
in the study population, the study authors estimated.

The authors noted limitations, such as their inability to ensure that women who were
dispensed a prescription actually used it. They added that the results do not provide
information on women ages 50 years and older and that they were not able to adjust
for some confounding factors (e.g., breastfeeding).

“It has been suggested that recent downward trends in ovarian cancer mortality
rates in North America and Europe can be partly attributed to the use of combined
oral contraceptives,” the authors wrote. “We found a population prevented
fraction of 21% with use of hormonal contraception, which supports the notion that
these ovarian cancer mortality benefits are likely to continue.”

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